6Alternating between romaine and radicchio, place six pieces of lettuce (3 romaine and 3 radicchio) on each of four plates, touching in center. In between each slice of lettuce, place a cherry tomato. Place a fish on each plate and evenly distribute tomato-onion mixture on top. Stir pan juices into vinaigrette and drizzle on top of the fish. Serve immediately.